This book deals with the interaction between mobile telephone antenna and the human body. Where mobile telephones are typically used in close proximity to the head, significant levels of power can be absorbed. The primary effect is to cause local heating of the brain, and head tissue. This is of concern to some people who work continually with mobile telephones, and some form of preventative research should be done. This book presents: Brief review about the different numerical methods used to model electromagnetic problems Research work done by using the method of Auxiliary Sources in investigating the effects of EM radiation on a sphere modeled a human head An application of using a new formula of a Green’s function in 3D, with the method of Auxiliary Sources Results of the simulation of a human body model and a cylindrical dipole antenna by using Method of Moment Results of the simulation of a homogeneous human head and a monopole handset antenna by using Method of Moment at 900 and 1800MHz Design method for the Microstrip antenna and simulation results by using FDTD method FDTD code program written in Matlab for the simulation of the Microstrip antenna